The Zacuto Z-UD is a universal donut which connects to the 105mm matte box, its inner elastic ring stretching to fit any lens between 40-85mm. Featuring a flexible frame and attaching via hook & loop fasteners, the donut can also fit the Petroff matte box.
Note:
Flexible donut. Attaches to matte box via a hook & loop (i.e., touch-tab) attachment.